Vapor generator and multipass superheater with a vapor temperature control system



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VAPOR GENERATOR AND MULTIPASS SUPERHEATER WITH A VAPOR TEMPERATURE CONTROL SYSTEM Filed NOV. 16, 1950 2 ShSG'S-Sheet 2 OOOOOOOOOOOOOOOOOOO O 1 OOOOOOOOOOOOO OOOOOOOOOOO OOOOOOOOOOOOO ai |g OOOOOOOOOOOOO OOOOOO OOO OOOOOOOOO OOOOOOOOOOOOOO OOOOOOO OOOO OOOOOOOO INVENTOR ATTO R N EY heatingsurface is provided toattain'a steam de# livery temperature of 850 F. when the unit 1s operating at a fractional load of approximatelyi 39,000 lbs. of steam per hour. f. Y

At full load the steam temperature F. unless means are provided to abstract some -of its heat. A submerged surface attemperator of the drum the inner passages of the tubularelements are not directly connected with the drumlspace but are connected by inlet conduit V62 and valved outlet conduit 56 to the inlet header space and the outlet header space, respectively, of the fourth steam pass elements.A

When valve 68 is opened a portion of the superheatedl steam leaving the third pass flows through G2, 64, B8, and 66, while the remaining portion ows through elements 56--58 of the fourth pass. As the iiow resistance through the elements 56-58 is quite high in the load range above the control point of 39,000 lbs. per hour, opening the valve 68 permits a flow of steam through the attemperator and that steam gives up some of its heat to the water of the steam and water drum. With this arrangement a simple thermostatically controlled valve 68 and short and simple piping can be used between the superheater headers and the attemperator. y Maximum flow through the attemperator will be permitted at maximum load, while at the control point load of approximately 39,000 lbs. per hour, valve $8 will be closed.

Steam from the steam connector or conduit 66 passes through the nozzle 61 into the outlet leaving the superheater will be appreciably in excess of 850A headercomponent of the fourth steam pass whichis also the inlet header component, of the last steam pass. This headercomponent is connected to the outlet header component T4 (separated from 48 by the diaphragm 52) by a bank of U-tubes such as 16 and 18 arranged as pre- Y viously described. The flow of steam in the last steam vpass of the `superheater is indicated by the arrow 80.

It is to be noted from an inspection of Figs.

2 and 3 that the outlet ends for the U-tubes of f the intermediate steam pass are connected to the outlet header component 50 of that pass at the side of that header component directly opposite the side to which the nozzle 61 is connected.`V U-tubes representative of the U-tubes of this intermediate control pass are indicated at 56 and 58 in the drawings. of nozzle and U-tubes relative to the header component .50 andthe tubular connector 66 leading This arrangement from the attemperator to the control-pass promotes effective mixing of the attemperated steam and the unattemperated steam, such mixing taking placev before the steam has passed very far axially of the header component 50. This arrangement is also effective in avoiding unbalance thereof. The dwntake headers 84 areconnected to the water space of the drum |0 by a series of connectors 88, and these downtake headers are connected` at their lower ends to a lower transverse header of mud-drum 90. The uptake headers 86 are individually connected by large diameter circulators Q2 with the drum I0. Beneath the banks of steam generating tubes and the superheater is furnace 94, the side walls of which include other steam generating tubes such as tit-98 kconnected into the circulation system of the installation by a connection at their lower ends to the header |00 and at their upper ends by connection to the uptake header |02. The latter has connected thereto risers such asj|04 and |06 leading to the steam space of the drum l0, the upright portions of these risers being disposed between the exterior casing |08 and the refractory furnace wall ||0 and the wall deiined by the headers B6. The downtake furnace header |00 is connected tothe water space oi the drum I0 by a plurality o downtake tubes such as ||2 and H4,I the lower parts of which are disposed between the refractoryy furnace wall ||6 and theexterior casing wall H8 through the latter of which one or more burners such as |20 are disposed, for iir-y ing the furnace. The oor of the furnace` is indicated at |22.

The installation shown is a` single pass installation in which the gases pass from the furnace 94 flow upwardly across the steam generating tubes of the bands {il-82, across the tubes i'orming the dierent steam passes ofthe superheater, and across the transverse tubular'elements of an airheater |24.

The superheater headers, as indicatedin Fig. 2 of the drawings, are disposed between the inner side wall |2 and the outer casing wall |28, with the U-tubes connecting those headers extending to pointsof adjacency relative to the opposite side wall |30. The illustrative steam generating and superheating installation is of a type which haslong been successful in marine use, and, with the particular improvements involved in this invention it provides for the generation of steam andthe superheating of the generated steam insuch a manner that the i'lnaltemperature of the steam will be maintainedat an optimum value withf out the use of expensive equipment such as ,three way control valves, and without the use of steam flow controlling oriiices. K v, Invention provides an arrangement of a combination of steam generating, a steam superheating land superheated steam attemp'eration apparatus which involves a minimum in weight and space `requirement of piping external of the setting for use in regulating the final delivered temperature of the superheated steam through Wa wide range of boiler rating. By using U-type elements, the inlet and outlet headers for the elements of the control pass are both located on thesame sideof the boiler, and this permits the attemperator pipingto be on one side of the setting. i

While the invention has been described with reference to the particular embodiment shown in the drawings, it is to be appreciated that it isnotlimited to all of the details thereof.-A 'The invention is rather to be considered as of a scope commensurate with the scope of theY subjoined claims. Whatis claimed is:v l jv l. In a'vaporsuperheater, an arrangement'- f 5 tubular elements forming at least three vapor passes across a heating zone, said passes being connectedv for series iiow oi the vapor across said zone. an attemperator connected in parallel relative to the tubular elements in an intermediate pass of vapor iiow, and mea-ns .tor varying the division or vapor iiow between said intermediate pass and the attemperator to maintain an optimum vapor temperature at the outlet of the superheater.

2. In a vapor super-heater, an arrangement of U-shaped tubular elements forming at least three vapor passes across a heating zone, said passes being connected for series flow of the vapor across said zone, an attemperator con nected in parallel relative to the tubular elements in an intermediate pass of vapor flow, and means for varying the division of vapor flow between said intermediate pass and the attemperator to maintain ancptimum vapor temperature at the outlet of the superheater, the attemperator being characterized by a pressure drop less than that of, its related intermediate pass. .i

3, Ina steam generating and superheating installation, walls forming a gas pass, spaced steam generating tubes extending across the gas pass and connected into afcirculating system, said system including a steam and water drum connected to the steam generating tubes, a convection superheater including an arrangement of header connected U-tubes extending back and forth across the gas pass and conducting steam across the gas pass in a plurality of three or more serially connected steampasses, an attemperator,

one of said passes intermediate the first and last being arranged and connected in parallel with the attemperator and having a free steam ilow area less than that ofthe attemperator, and a steam now controller regulating the division of steam between the attemperator and the tubes of said intermediate pass to maintain the temperature of the steam at the outlet of the superheater at an optimum value.

fi. In a steam generating and superheating installation, Walls forming a gas pass, steam generating tubes extending across the gas pass and connected into a` circulating system, said system including a steam and water drum connected to the steam generating tubes, a convection superheater including an arrangement of header connected tubes extending across the gas pass and conducting steam back and forth across the gas pass in a plurality of three or more serially connected steam passes, an attemperator disposed Within the water space of the drum, one of said passes intermediate the iirst and last being arranged and connected in parallel with the attemperator, and a steam flow controller regulating the division of steam between the attemperator and the tubes of said intermediate pass to maintain the temperature of the steam at the outlet of the superheater at an optimum value.

5. In a steam generating and superheating installation, walls forming a gas pass, spaced steam generating tubes extending across the gas pass and connected into a circulating system, said system including a steam and Water drum connected to the steam generating tubes, a convection superheater including an arrangement of header connected U-tubes extending back and forth across the gas pass and conducting steam across the gas pass in a plurality of three or more serially connected steam passes, an attemperator, one of said passes intermediate the first and last being arranged and connected in parallel with the attemperator and having a steam free flow area less than that of the attemperator, and a steam flow controller regulating the division of steam between the attemperator and the tubes of said intermediate pass to maintain the temperature or the steam at the outlet of the superheater at an opimum value.

` 6. In a vapor superheater, an arrangement of U-shaped tubular elements forming at least three vapor passes across a heating zone, said passes being connected for series iiow of the vapor :across said zone, an attemperator connected in parallel relative to the tubular elements in an intermediate pass of vapor flow, and means including a tbermostatically operated valve for varying the division of vapor flow between said intermediate pass and the attemperator to maintain an optimum vapor temperature at the outlet of the superheater.

7. In a fluid heater, an arrangement of tubular elements forming at least three fluid passes across a heating zone, said passes beingconnected for series iiow of the fluid across said zone, an attemperator arranged in parallel relative to the tubular elements in an intermediate pass of vapor flow, and means for varying the division of iiuicl flow between said intermediate pass and the attemperator to maintain an optimum fluid temperature at the outlet of the heater` 8. In a steam generating and superheating installation, walls forming a gas pass, spaced steam generating tubes extending across the gas pass and connected into a circulating system, said system including a steam and water drum connected to the steam generating tubes, a convection superheater including an arrangement of header connected U-tubes extending across the gas pass and conducting steam back across the gas pass in a plurality of serially connected steam passes, one of said passes intermediate the rst and last having a number of U-tubes therein smaller than the number of U-tubes in the other passes and arranged and connected in parallel with the attemperator, an inlet header component for the intermediate steam pass, an outlet header component for the intermediate steam pass having the intermediate steam pass U-tubes joined to the latter header component at one side thereof, a tubular connector leading from the intermediate steam pass to the attemperator, a conduit nozzle joined to the latter header component on its side opposite the U- tube connections, a tubular connector leading from the attemperator to said nozzle, and a steam now controller regulating the steam now to the attemperator to maintain the temperature of the steam at the oulet of the superheater at an optimum value. y

STODDARD S. WALDRON.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date` 2,133,991 Kerr Oct. 25, 1938 2,276,326 Martensson Mar. 17,-1942 2,386,188 Artsay Oct. 9, i945 2,392,325 Kuhner Jan. 8, 1946 FOREIGN PATENTS Number Country Date 368,007 Great Britain Mar. 3, 1932 472,192 Germany Apr. 2, i927 

